You cannot just fool around with it like with sound: Besides the much higher bandwidth (~5MHz) which makes designing video circuits much more demanding, the main problem is that video signal contains not only the actual picture, but also synchronization signals. You touch the picture and the sync goes away, the screen starts shaking… Try to fade a video signal to black like you would with audio – no way to do this with just a potentiometer. Instead of a nice appeasing black you’ll get a crazy light storm capable of generating epileptic seizures…

We’d like to create a system that lets us experiment with an analog video signal as you can do with sound, like filtering, applying lfos, making lo-fi 8bit stuff, … fool around … without losing sync. A modular system somewhat like the Doepfer A100 but for video.

The basic idea is to separate the the picture portion of the signal from the sync, do anything you want with it, and merge it back to the sync at the end.

Sync Signal

That’s basically just a black picture, retaining all the sync pulses and colorbursts:

Picture Signal (or Siff-signal)

Siff is a swiss-german word for trash. The siff signal is the one we modify, tool around and let get dirty:

This signal goes through a series of modules that can be patched together in real time with cinch cables, where it is modulated and destroyed. At the end of the chain is the sk02 resyncer module, which cuts the synchronisation portion of the original signal back into place.

For now we focus on developing the first and the last module of this chain the one that separates and the one that recombines the signal.

Next modules could be:

Clip and offset

Mixer

Y/C separator & merger

Filters

The first modules have been built today, but we’re seeing strange behaviour. Much too much gain at the output of the sync separator, oscillating op-amps, impedance problems…